title: Electron microscopy observation of TiO2 nanocrystal evolution in high-temperature atomic layer deposition.
abstract: Understanding the evolution of amorphous and crystalline phases during atomic layer deposition (ALD) is essential for creating high quality dielectrics, multifunctional films/coatings, and predictable surface functionalization. Through comprehensive atomistic electron microscopy study of ALD TiO2 nanostructures at designed growth cycles, we revealed the transformation process and sequence of atom arrangement during TiO2 ALD growth. Evolution of TiO2 nanostructures in ALD was found following a path from amorphous layers to amorphous particles to metastable crystallites and ultimately to stable crystalline forms. Such a phase evolution is a manifestation of the Ostwald-Lussac Law, which governs the advent sequence and amount ratio of different phases in high-temperature TiO2 ALD nanostructures. The amorphous-crystalline mixture also enables a unique anisotropic crystal growth behavior at high temperature forming TiO2 nanorods via the principle of vapor-phase oriented attachment.
authors.affiliation: Department of Materials Science and Engineering and ‡Materials Science Center, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Jian
authors.initials: J
authors.lastname: Shi
authors.forename: Zhaodong
authors.initials: Z
authors.lastname: Li
authors.forename: Alexander
authors.initials: A
authors.lastname: Kvit
authors.forename: Sergiy
authors.initials: S
authors.lastname: Krylyuk
authors.forename: Albert V
authors.initials: AV
authors.lastname: Davydov
authors.forename: Xudong
authors.initials: X
authors.lastname: Wang
mesh_terms: D003460:Crystallization; D006358:Hot Temperature; D018625:Microscopy, Atomic Force; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D049329:Nanostructures / Q000737:chemistry / Q000648:ultrastructure; D043942:Nanotubes / Q000737:chemistry; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D014025:Titanium